The present invention relates to a process for development of silver halide photographic photosensitive materials and more particularly, to a photographic photosensitive material which can produce a negative image of extremely high contrast and a negative image of high sensitivity and provide good dot image quality.
To add a hydrazine to silver halide photographic emulsions or developers has been known in U.S. Pat. No. 3,730,727 (developer containing ascorbic acid and hydrazine in combination), U.S. Pat. No. 3,227,552 (use of hydrazine as auxiliary developer for obtaining direct positive color image), U.S. Pat. No. 3,386,831 (.beta.-monophenylhydrazides of aliphatic carboxylic acids contained as stabilizer for silver halide photosensitive materials), U.S. Pat. No. 2,419,975, and Mees, "The Theory of Photographic Process", the third edition, (1966), page 281.
Among them, especially U.S. Pat. No. 2,419,975 discloses that high contrast negative images are obtained by addition of hydrazine compounds.
That is, it is disclosed that when a hydrazine compound is added to a silver chlorobromide emulsion and this emulsion is developed with a developer of a high pH of 12.8, photographic characteristics of very high contrast of more than 10 in gamma (.gamma.) can be obtained.
However, a highly alkaline developer having a pH of near 13 is readily oxidized with air, is unstable and cannot be stored or used for a long term. Photographic characteristics of super-high contrast of more than 10 in gamma value are very useful for photographic reproduction of continuous tone image through dot image useful for printing plate or reproduction of line image irrespective of negative image or positive image.
For such purpose, a process has been employed in which a silver chlorobromide emulsion containing at least 50 mol %, preferably more than 75 mol % of silver chloride is used and development is carried out with a hydroquinone developer having very low effective concentration of sulfite ion (usually at most 0.1 mol/l) (lith development).
However, according to this process, since concentration of sulfite ion in the developer is low, the developer is extremely unstable and cannot be stored for more than 3 days.
In addition, these processes require to use a silver chlorobromide relatively high in silver chloride content and so a high sensitivity cannot be obtained.
Under the circumstances, it has been strongly desired to obtain super-high contrast photographic characteristics useful for reproduction of dot image and line image by using an emulsion of high sensitivity and stable developer.
For this purpose, silver halide photographic photosensitive materials which can provide high contrast negative photographic characteristics with using a stable developer are disclosed in U.S. Pat. Nos. 4,168,977, 4,224,401, 4,243,739, 4,269,929, 4,272,614, and 4,323,643. However, it has been found that acylhydrazine compounds used in these materials have some defects.
That is, these hydrazines are known to generate nitrogen gas during development treatment and this gas may collect in the film to form bubbles and may damage photographic images.
Therefore, compounds which can provide very high contrast photographic characteristics even with small addition amount have been demanded in order that generation of the bubbles can be decreased and simultaneously, cost for production of photosensitive materials can be reduced. Furthermore, if development is continued using these hydrazines, innumerable circular fogs (pepper fogs) are readily generated in unexposed area and image quality has been seriously damaged.
Moreover, the conventional hydrazines must be used in a large amount for obtaining high contrast and for sensitization and it is desired to use them in combination with other sensitizing means (for example, strong chemical sensitization; increase in grain size; addition of compounds which accelerate sensitization as mentioned in U.S. Pat. Nos. 4,272,606 and 4,241,164) when especially high sensitization is required as performance of photosensitive materials. However, if these sensitizing means are employed in combination with the hydrazines, sensitization and increase of fog with time may occur during storage.
Furthermore, if development is carried out with conventional hydrazines, so-called unevenness of development is apt to occur owing to uneven stirring of the developer. This unevenness of development occurs conspicuously when development is conducted by automatic processor and if development treatment is strengthened for avoiding this phenomenon, the above-mentioned pepper fogging phenomenon occurs.
Therefore, a compound has been demanded which is free from the above-mentioned problems in stability with time and the problems such as unevenness of development and pepper fog and is effective with addition of it in a small amount and besides, can be easily prepared.